﻿/*
 * Copyright © 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

namespace Spring.Objects.Factory.Support;

/// <summary>
/// Convenience implementation of the <see cref="IFactoryObject"/> interface that
/// delegates to an arbitrary object + method to perform the object construction.
/// </summary>
/// <remarks>
/// <para>
/// Because this <see cref="IFactoryObject"/> implementation requires a delegate
/// passed to its ctor, its only possible to configure this object and register
/// it with the <see cref="IObjectFactory"/> via code rather than via XML.
/// </para>
/// </remarks>
/// <typeparam name="T"></typeparam>
public class DelegateInvokingFactoryObject<T> : IFactoryObject
{
    private readonly bool _isSingleton;
    private readonly Func<T> _builderDelegate;

    /// <summary>
    /// Initializes a new instance of the <see cref="DelegateInvokingFactoryObject{T}"/> class.
    /// </summary>
    /// <param name="builderDelegate">The builder delegate.</param>
    /// <param name="isSingleton">if set to <c>true</c> [is singleton].</param>
    public DelegateInvokingFactoryObject(Func<T> builderDelegate, bool isSingleton)
    {
        _builderDelegate = builderDelegate;
        _isSingleton = isSingleton;
    }

    /// <summary>
    /// Return an instance (possibly shared or independent) of the object
    ///             managed by this factory.
    /// </summary>
    /// <remarks>
    /// <note type="caution">If this method is being called in the context of an enclosing IoC container and
    ///             returns <see langword="null"/>, the IoC container will consider this factory
    ///             object as not being fully initialized and throw a corresponding (and most
    ///             probably fatal) exception.
    ///             </note>
    /// </remarks>
    /// <returns>
    /// An instance (possibly shared or independent) of the object managed by
    ///             this factory.
    /// </returns>
    public object GetObject()
    {
        return _builderDelegate.Invoke();
    }

    /// <summary>
    /// Return the <see cref="T:System.Type"/> of object that this
    ///             <see cref="T:Spring.Objects.Factory.IFactoryObject"/> creates, or
    ///             <see langword="null"/> if not known in advance.
    /// </summary>
    public Type ObjectType
    {
        get { return typeof(T); }
    }

    /// <summary>
    /// Is the object managed by this factory a singleton or a prototype?
    /// </summary>
    public bool IsSingleton
    {
        get { return _isSingleton; }
    }
}
